The present invention is directed to a device for cutting glass fibers which device has an anvil, a pair of clamps on each side of the anvil for clamping the fibers with each of the fibers extending parallel to each other over the anvil and means for moving the clamps to prestress the fibers in an axial direction so that when the fibers are subsequently notched or scratched while on the anvil with the assistance of a notching or scratching tool which is moved in a direction perpendicular to the axis of the fibers, the fibers will be separated at the point of notching.
A typical device for separating glass fibers is described in U.S. Pat. No. 4,315,584 which was based on German LP No. 29 25 070. As disclosed in this patent, fibers are clamped on each side of an anvil with the clamps being moved apart while a chisel or cutting tool scratches or notches the fibers to allow separation at the point of the notch. In this and other known devices of this type, the end faces of the cut glass fibers do not exhibit the precision which is required for further use so that subsequent working steps at the end face are necessary. It has turned out that only approximately 30% of the notched cut glass fibers exhibit a usable cleavage face which is determined as the angular deviation of the cut surface being less than 1% relative to the fiber axis and the quality of the cut surface is free of disruptive notches, cracks and other irregularities.